The health risks of UVA and UVB light to the human eye and skin have been well documented. Recently short wavelength visible light, both violet and blue, were shown to be damaging to cells both in in vitro and in vivo studies reported in Experimental Eye Research 2006, 83, 1493; J. Cataract Refrac Surg 2009, 35, 354; Graefe's Arch Clin Exp Ophthalmol 2008, 246, 671; Acta Ophthalmologica Scandinavica 2006, 84, 4; Br J Ophthalmol 2006, 90, 784; Optometry and Vision Science 2011, 88(6), 1 (herein incorporated by references in their entireties). It would be advantageous to have violet and blue light blocking contact lenses which can block some light in the region of 380 nm to 460 nm.
UV absorbers are known as ingredients for polymeric materials used to make ophthalmic lenses. Such absorbers are preferably polymerizable so as to be covalently bound to the polymeric network of the lens material instead of simply physically entrapped in the material, thereby preventing them from migrating, phase separating or leaching out of the lens material. Such stability is particularly important for ophthalmic lenses because the leaching of the absorber may present both toxicological issues and lead to the loss of UV/visible blocking activity of the ophthalmic lenses.
Polymerizable benzatriazole, benzophenone and triazine absorbers are known. Most of these compounds are known as UV absorbers, though some may be known to also absorb some portion of visible light. Many absorbers contain ethylenically unsaturated groups, such as methacrylate, acrylate, methacrylamide, acrylamide or styrene groups. Copolymerization with other ingredients in the lens materials incorporates the absorbers into the resulting polymer chain.
U.S. Pat. Nos. 8,153,703, 8,232,326, 8,262,947, and 8,585,938 (herein incorporated by references in their entireties) disclose benzotriazole vinylic monomers which can block HEVL. Although the benzotriazoles vinylic monomers are typically photo-stable and can absorb a large amount of both visible and UV light, they may be difficult and expensive to make. Also, they may not be soluble in a lens formulation. If the absorber does not have sufficient solubility in a lens formulation, the absorber may coalesce into domains that could interact with light and result in decreased optical clarity of the lens.
WO2014/018208 (herein incorporated by reference in its entirety) recently discloses new UV/visible light absorbing vinylic monomers with anthraquinone structures. Anthroquinone vinylic monomers may not have a desired photo-stability for use in ophthalmic lenses.
There is a need for a visible light absorbing vinylic monomer that absorbs lights between 380 and 460 nm, shows good solubility in formulations, is photo-stable, and is inexpensive to make.